The invention relates to a circuit arrangement for feeding electrical users with a DC voltage wherein at least one user is connected via a first switch controller to a feed circuit fed with an impressed current. The switch controller has at least one switch element controllable by a control circuit supplied from an auxiliary voltage source.
Such a circuit arrangement is already disclosed by German OS No. 32 42 023 or by German OS No. 32 21 404, both incorporated herein by reference.
The circuit arrangement of German OS No. 32 42 023 discloses a constant-current-fed converter which generates a constant, potential-separated voltage for a variable load in such fashion that a correspondingly regulated inductance converter converts a variably accepted voltage into a stabilized voltage. The stabilized voltage is somewhat higher than the input voltage allocated to the maximum power. The output voltage is generated from the stabilized voltage potential separated by an unregulated flow converter.
Converters which are fed by a current held constant and which match their input voltage to the respectively required output power can not be supplied with auxiliary voltage without further work, like standard converters which are operated from a voltage source, since this auxiliary voltage can only be derived with greater expense both from the input voltage as well as from the output voltage. The input voltage varies greatly and the output voltage is so high, given higher powers, that either special components are required and/or higher leakage losses arise.
Also, a protection against influencing currents is not possible without further work for such devices since they reduce their output voltage with increasing input current and, for example, surge arresters such as are standard for ohmic situations, do not respond. The high currents which then flow could, however, destroy the device.